Silicon-polybutadiene resins

ABSTRACT

Silicone-polybutadiene resins wherein a siloxy-terminated polybutadiene having vinyl groups on alternate carbon atoms of the diene backbone is condensed by means of functionality on the silicon atoms with a hydroxyl-functional organo-silicon resin, the vinyl groups of the diene being cyclized by means of an organic peroxide catalyst, have utility as protective coatings.

United States Patent Antonen et al. Get. 9 1973 [54]SILICON-POLYBUTADIENE RESINS 3,281,383 10/1966 Zelinski et al. 260/23]E2 7 3,470,226 9/1966 Plumb et al 260/94.7 R X [75] Inventors RbertAmmen; 3,655,598 4/1972 Antonen et al... 260/18 s Kookootsedes, both ofMidland, Mich. f 2, a Primary ExaminerJoseph L. Scho er [73] Asslgnee' 39 Commg Corporation Mldland Assistant ExaminerWilliam F. Hamrock 2AttorneyR0bert F. Fleming, Jr. et a1. [22] Filed: Nov. 24, 1971 [21]Appl. No.: 202,033 [57] ABSTRACT Related US. Application Data [62]Division of $81. No. 50,987, June 29, 1970, Pat. No.slhcone'pclybutadlene resms a 3,333,061 terminated polybutadiene havingvinyl groups on a]- ternate carbon atoms of the diene backbone is con- 5CL 260/94; R 260/18 S, 260/465 p, densed by means of functionality onthe silicon atoms 260/94] A, 260/94] 260/94] R with ahydroxyl-functional organo-silicon resin, the 511 int. Cl. C08d 5/02,C08d 5/04 vinyl groups of the diene being cyclized by means of [58]Field of Search 260/947 A, 94.7 R, an Organic Peroxide Catalyst, haveutility as Protective 260/947 HA, 18 S, 46.5 P, 94.21 coatmgs- [56]References Cited 7 Claims, N0 Drawings SILICON-POLYBUTADIENE RESINS Thisis a division of application Ser. No. 50,987, filed June 29, 1970 nowU.S. Pat. No. 3,333,067.

This invention relates to silicone-polybutadiene resins. In one aspect,the invention relates to improved curable compositions useful ascoatings for electrical coils and circuitry, as paitns, as resins forlaminates and as molding compounds.

the invention provides siloxy-terminated butadiene polymers of thegeneral formula II on,

in which R is a monovalent hydrocarbon radical of from one to 18inclusive carbon atoms; X is a hydrolyzable radical selected from thegroup consisting of the chlorine atom, alkoxy radicals of from one tosix inclusive carbon atoms, acyloxy radicals of no more than eightcarbon atoms and ketoxime radicals; a is an integer having a value of lor 2 and n is an integer having a value sufficiently high to provide apolydiene average moelcular weight in the range ofrom about 500 to3,000.

R can be any monovalent hydrocarbon radical of no more than l8 carbonatoms, for example, alkyl radicals, such as methyl, ethl, isopropyl,hexyl, dodecyl or octadecyl; alkenyl radicals, such as vincyl, allyl,hexenyl or propargyl; cycloaliphatic radicals such as cyclopentyl,cyclohexyl or cyclohexenyl; aromatic h drocarbon radicals such asphenyl, tolyl, xylyxl, xenyl, or naphthyl and aralkyl radicals such asbenzyl, betaphenylethyl, beta-phenylpropyl or gamma-tolylpropyl.

Preferred R substituents are the methyl, pheynl and.

vinyl radiacals. The R usbstitutents on the same silicon atom can be thesame or different and the two silicon atoms can contain the same ordifferent R groups.

The hydrolyzable groups include the chlorine atom; alkoxy radicals, suchas methoxy, ethoxy or butoxy; acyloxy radicals, such as acetoxy,propionyloxy or benzoyloxy, and ketoxime radicals of the formula ON=CZor N=CZ' in which Z is a monvalent hydrocarbon r radical such as thoseshown for R, and Z' is a divalent hydrocarbon radical, both valences ofwhich are attached to the carbon atoms, such as hexylene, pentyleneoctylene or The preferred alkoxy radicals are thos having from one tosix inclusive carbon atoms, preferred acyloxy radicals are those havingless then eight carbon atoms. The ketoxime-functional silanes are wellknown as shown in U.S. Pat. No. 3,189,576.

These siloxy-terminated polybutadienes are prepared by reacting silanesof the formula X SiR, in which X and R are as defined above and b is aninteger having a value of 2 or 3, with dihydroxyl-terminated 1,2-polybutadicne. This chain extending reaction occurs at room temperatureand can be carried out in a suitable solvent, such as toluene, xylene ortetrahydrofuran. To prevent premature hydrolysis of the siloxyfunctionality and gellation of the product the materials are reactedunder anhydrous conditions. The condensation product, such ashydrochloric acid or methanol, can be removed by distillation orneutralizing the reaction mixture.

The dihydroxyl polybutadiene can be prepared by anionic polymerizationof l,3-butadiene in a solvent system containing an alkali metal toproduce an alkali metal terminated polymer which is subsequently reactedwith ethylene oxide and acidified to provide the hyroxyl functionality.The polybutadiene resin, containing pendent vinyl groups on alternatecarbon atoms of the polymer backbone, and details of its preparation aredisclosed in U.S. Pat. No. 3,431,235. The silanc rcactants are wcllknownmaterials and include methyltrichlorosilane, phenylmethyldichlorosilane,ethyltrimethoxysilane, phenyltriethoxysilane, octylmethyldibutoxysilane,vinyltriacetoxysilane and methyltrikctoximesilane.

The siloxy-terminated polybutadienes of the invention can be applied toa variety ofsubstrates and will air dry to provide a soft resionoustacky coating having adhesive properties. The air curing propertyresults from the hydrolysis of the siloxy functionality in the presenceof atmospheric moisutre. For example aluminum panels can be coated witha solution of the polymer and the solvent evaporated to provide anadhesive coating. A relatively hard resinous coating can be obtained bydispersing an organic peroxide catalyst in the resinous material andheating to about 150C. the generation of free radicals promotescross-linking and the cyclization of pendent vinyl groups on the dienebackbone to form fused cycloaliphatic groups giving a hard thermosettingresin which serves as a protective coating for substrates, such as metalor wood.

Typical of the organic peroxide free radical generatiors are di-t-butylperiodide; 2,5-dimethyl-2,5- bis(tertiary butylperoxy)-hexane;n-butyl-4,4- bis(teritiary butylperoxy) valeratc; tertiary-butylperbenzoate; dicumyl peroxide; cumene hyperoxide; actyl peroxide;di-n-methyl-t-butyl percarbamate; t-butyl peracetate and t-butylperoxyisobutyrate. Generally 0.5 to 5 weight percent, based on theweight of resin, of the peroxide catalyst is used.

The invention also provides curable compositions consisting essentiallyof a. 5 to 45 weight percent of a siloxy-terminated polybutadiene of thegeneral fonnula i011 RB-n in which R is a monovalent hydrocarbon radicalof from one to l8 inclusive carbon atoms, X is a hydrolyzable radicalselected from the group consisting ofthe chlorine atom, alkoxy radicalsof the chlorine atom, alkoxy radicals of from one to six inclusivecarbon atmos, acyloxy radicals of no more than 8 carbon atoms andketoxime radicals, a is an integer of l or 2 and n is an integer havinga value sufficiently high to provide a polydiene average molecularweight of from about 500 to 3,000; and

b. 55 to 95 weight percent of a hydroxyl-functional organosiliconresinconsisting essentially of units of the formula R' SiO in which R is amonovalent hydrocarbon radical of from 1 to 6 inclusive carbon atoms, atleast mol percent of the R substituents being selected from the groupconsisting of the methyl radical and the phenyl radical and c has anaverage value of from 1 to 1.7, the organosilicon resin having asilicon-bonded hydroxyl content of from 1 to weight percent, based onthe weight of the resin.

The hydroxyl-functional organosilicon results are well-known and includethose containing units such as a m Qh z s m a 5 m, (C H SiO, CH (Cl-l=CH)SiO, C l-l,(C l-l )SiO, CH (C H )SiO, (Cl-19 5m C H (CH =CH)SiO andthe like. These resins are easily prepared by hydrolysis of thecorresponding chlorosilanes. Since it is desired to form a hard resinousproduct, at least 70 mol percent of the R substituents must be methyl orphenyl radicals and the degree of substitution or average number oforganic substituents per silicon atom must be in the range of from 1 to1.7. Hard rigid products are obtained when resinshaving a low d.s.(degree of substitution) are used. In most end uses a certain amount offlexibility is desired, therefore resins having a d.s. in the range offroml.3 to 1.5 are preferred.

The hydroxyl-functionality of the organosilicon resin provides reactivesites for condensation with the 27SiX functionality of thepolybutadiene. This coupling of components (a) and (b) results in acompatible resin copolymer. The coupling reaction can be carried out ina suitable solvent, such as toluene at room temperature. The couplingreaction need not be catalyzed but the rate of reaction can be increasedby the addition of mild condensation catalyst, such as the wellknownamine or titanate catalyst, when the less reactivealkoxysilane-functionality is present in the polybutadiene. V

The above-described compatible resin composition can be cured by meansof two different mechanisms. First is by condensation of any silanolfunctionality remaining in the compatible resin composition. Thiscondensation is affected by heating the resin at 1509C. or more in thepresence of condensation catalysts such as dibutyl tin diacetate, leadnaphthanate, cobalt naphthanate, zinc naphthanate, ferric octoate,chromium octoate, lead 7 -ethylhexoate, dibutyl tin dibenzoate,dibutyltin adipate and lead sebacate. These are representative of theclass of catalysts known in the art as the carboxylic salts of metalsranging from lead to maganese inclusive in the electro-motive series ofmetals. Other examples of classes of conventional silanol condensationcatalysts, such as amines and titanates, are found in the prior art. Thecondensation catalysts are used in an amount in the range of from about0.05 to 5 weight percent, based on the weight ofthe organosilicon resincomponent (b).

In a second curing system organic peroxide free radical generators, suchas those described above, can be used in combination with the silanolcondensation catalyst to provide a dual catalyst system for curing thecomposition. The organic peroxides are added in an amount in the rangeof 0.5 to 5 weight percent, based on the weight of resin (a). Theabove-described composition is heated at elevated temperatures to obtainthe cured resinous product. Heating to temperature of from 150 to 300C.for l ensures completion of both the condensation and cyclization curingreactions.

If desired, theorganic peroxide catalyst can be used alone, relyingentirely upon the cyclization of the polydiene to provide the curing.This is especially desirable when an organosilicon resin (b) having alow silanol content is used in forming the compatibleresin composition.

A preferred embodiment of the invention resides in a compositionconsisting essentially of (a) 10 to 30 weight percent of the previouslydescribed siloxyterminated polybutadiene in which the hydrolyzable groupis an acyloxy radical and (b) to weight percent of the describedorganosilicon resin in which all of the R substituents are selected fromthe group consisting of methyl and phenyl radicals. This composition hasparticular utility in the coatingof metal articles.

The curable compositions of the invention are particularly suitable forcoating pipes, containers and other items which are exposed to hightemperatures and corrosive materials. Small amounts of otherorganopolysiloxanes can be added to the resin if it is desired to modifythe properties of the cured product. For example, one weight percent ofaphenylmethylpolysiloxane fluid can be added to give cured coatings whichhave release properties. Pigments and other fillers, such as silica. canalso be added to the curable compositions.

The following examples are illustrative of the invention which is setforth in the claims.

EXAMPLE 1 (CHaCO) SiO CH;CH OHCH CI-I CH OSi (OICCIIQ) 9 II I H 1 CH2 nThe solution of siloxy-termi nated polybutadiene was added to a solutionof 300 gramsof organosilicon resin in 560 grams of toluene.

CH; CH;

the resin consisted of methyl and phenyl siloxy unitshaving a d.s. of1.15 and a silicon-bonded hydroxyl content of about 6 weight percent.The mixture ofresin solutions was stirred at room temperature for about2 hours after which the resin mixture was compatible indicating couplingbetween the siloxy-terminated resin and the organosilicon resin. A totalof 32 grams of calcium carbonate and 200 grams of toluene was added withstirring to the compatible resin in order to neutralize the acetic acidby-product of the reaction. The resin was filtered and about 200 gramsof toluene were removed by distillation to obtain a compatible resinproduct in a 40% solids solution of toluene.

Ferric octoate (0.1 weight percent) and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (1.0 weight percent) were added tothe resin. The catalyzed resin solution was coated onto steel panels andallowed to drair dry to form a tack free coating. The coatings werecured at about 200C. to obtain a hard resin film having excellentresistance to deterioration by steam and oil vapors.

EXAMPLE 2 Various amounts of vinyldiacetoxysilyl-endblockedpolybutadiene having polydiene average molecular weights of 1,000 and2,000 were mixed with various amounts of the hydroxyl-functional resindescribed in Example 1 to provide 50 percentsolutions of the compatibleresin in xylene. The resin solutions were catalyzed by the addition offerric octoate (0.2 weight percent) and2,5-dimethyl-2,5-bis(t-butylperoxy)hexane and 0.2 weight percent of aphenylmethyldimethylsiloxane copolymeric fluid was added to providerelease characteristics.

Steel panels were dipped in each of the catalyzed resin solutions,allowed to air dry for a few minutes, and cured for or 30 minutes at400F. The cured film on panels was evaluated for steam resistance, oilresistance, and slip angle. Steam resistance is determined by firstobserving the pencil hardness of the cured panel, placing the panel overa beaker of boiling water for 5 minutes, and again observing the pencilhardness of the cooled panel. Oil resistance is determined by placingthe panel over a beaker of heated smoking cooking oil for 5 minutes andafter cooling rubbing the panel with the peen end of a 3-pound ball peenhammer wrapped with four layers of cheese cloth. The coating is rated onthe number of double rubs with the hammer necessary to break through thesurface of the film. If double rubs are obtained, the panel is placedover the hot oil for an additional five minutes and the procedure isrepeated on a different section of the oil-exposed panel. This test isrepeated through five sysles. The slipangle is the minimum anglethatpermits a 154 gram weight (covered with cheese cloth) to slide down thepanel. All of the panels had a slip angle of from 5 to 6.

The various resin formulations and curing conditions are given in TableI. The physical characteristics of the cured coatings are set forth inTable II.

TABLE II -(ominucd Oil resistance (hammer rubs per cycle) Steamresistance Pencil hardness of the cured resin coating. Such a coatinghas particular utility in providing release of baked goods from pans.

EXAMPLE 3 Compatible resin-toluene solutions containing l0, l5 and 25weight percent of vinyldiacetoxysiloxyteriminated polybutadiene (averagemolecular weight of 2,000) were prepared. The organosilicon resincomponent, present in 90, 85 and 75 weight percent, consisted of 76.5mol percent C H SiOO 15 mol percent (CH SiO and 8.5 CH (C H )SiO unitsand had a E SiOHcontent of about 3 weight percent. These resinsolutions, 0containing 50 percent solids, were catalyzed by the additionof 0.7 weight percent of iron octoate and 0.4 weight percent2,5-dimethyl-2,5-bis(tbutylperoxy)hexane.

These resin solutions were formulated into paint compositions containing20 parts TiO 10 parts A1 0 1.5 arts of commercially available paintadditives and 65.5 parts of the 50 percent solid resin solution. Thepigmented resins were applied to aluminum panels by dip coating. Thecoatings were cured at 400F. for

TABLE 1 minutes. After cooling to room temperature, the mar resistance,hardness, gloss, and adhesion of the coatings were determined. Thestandard tests to determine P I d w h WeightCUE lNG crosscut adhesionand the Hoffman Scratch Test were 0y iene eig t Percent imc- 4 FormwMolecular Percent organo Minutes used. Crosscut adhesion IS determinedby making a se iation Weight Siloxysilicon at rles of parallel cutsthrough the film in one direction lliumber $886 8 g; 2"; and a secondseries of parallel cuts at right angles to the 2 2000 25 75 30 first.The cuts are preferably about l/32-inch. apart. 3 333 g8 g3 g3 Scotchtape is placed over the crosscut area and then 5 2000 I5 85 15 removed,the number of squares remaining intact give 6 2000 15 85 30 a quamtativemeaure of adhesion. The test IS described 888 :3 g8 as in detail in thePaint Testing Manual, Physical and 9 000 25 15 Chemical Examination,Paints, Varnishes, Laquers and :388 3 33 i2 Colors by Gardner and Sward,Twelfth Edition, l962. 12 I000 20 3O 50 The pencil hardness of thecoating was alsodeter- :3 1888 15 5 l5 mined at the 400F. temperature.15 3 The paint compositions and test results are given b0- m 1000 10 30low:

He lman Ewell ggosscnt scratch a hardness ata esi t Paint vehicle reslncomposition pcrcgri t val ii ti l cfifil i ll g Rt. 400 F.

10 wt. percent polybutadiene ilJg WE- percent orgarosilicon refsiiifiuni 3 63 2B 2B w percent po 31 utadiene r in 32 WE. pereengorglarosilicon res iix U} 100 4 53 2B 23 w percen 0 ut d 75 wt. percentrggnosi l icii ri 3551 5 100 5 53 1B 21? TABLE II EXAMPLE 4 Steamresistance Oil reslsta pencil hardness (hammer rubs g Trlacetoxysilaneswere reacted with hydroxyl- Formulaflon Before After Number cycles 65terminated polybutadienes and the siloxy-functional number exposureexposure 1 2 3 4 5 diene was then reacted with an organosilicon resinhav- 1 1% 2% 32 mg 1.9 weight percent silicon-bonded hydroxyl groups 2%3H 25 25 25 8 and consisting essentially of 15 mol percent cn,si0,,,, 4H3% 532 5;? 33 23 35 mol percent c,r-i,si,,,, 40 mol percent (CH SiO 6 4H4H 25 25 25 25 19 and 10 mol percent (C,H,) SiO units. Thepolybutaditure heated to about 130C., with distillate being removed withthe rise in temperature. After cooling, the

' described organosilicon resin and sufficient xylene to form a 60percent solution was added to the siloxyfunctional product. This mixturewas heated at 140C. until a compatible resin. solution was obtained.Compatibility is visually determined by observing film clarity.

The amount and molecular weight of the hydroxylfunctional polybutadienewas varied, as was the composition of the silane reactant. Thecompatible resin formulations were catalyzed with 0.1 weight percent,based on the weight of the resin, of ferric octoate. Peroxide catalystswere not used. Portions of the catalyzed resin solution were mixed withpigments and additives to form a paint composition based on 65 weightpercent of l 50 percent solids resin solution.

Each of the resin solutions and paint compositions were usedto dip. coataluminum panels. The coatings were cured for seconds at 250C. Tack-freefilms were obtained in all cases. Thickness, hardness and flexcharacteristics of the cured films were, determined.

7 Table NoQIll gives the resin formulation and Table IV the physicalcharacteristics of both the clear film and paint. v,

'AcO-designates ucetoxy radical.

TABLE IV This example demonstrates the use of the siloxyfunctional resinas-a binder for glass fabric and the resin 7 functions equally well withother fibers, such as silica carbon black, and the like.

EXAMPLE 6 A mixture of grams of dihydroxyl polybutadiene (molecularweightof about 2,000)and 5.6 grams of me-' thyltrichlorosilane in 50grams of toluene was reacted at room temperature to obtainmethyldichlorosiloxyterminated polybutadiene. Aluminum and steel panelswere dipped into solutions and allowed to air dry for 48 hours, giving asoft, tacky film. The air-dried films were cured at 350F. for 90 minutesto obtain a non-tacky coating having a pencil hardness of 2H.

About 1 weight percent of the peroxide catalyst described in Example lwas added to the resin solution and aluminum panels were coated with.the catalyzed resin. After air-drying for 30 minutes, the coatings werecured at 350C. forl hour to'give a relatively rigid resin having apencil hardness of 2H;

EXAMPLE 7 Amixt ure of 50 grams of the polybutadiene used in Example 6and 1 1.3 grams of yield methyLdi-methylethylketoxime siloxy-terminatedpolubutadiene. Films of the resin were coated onto aluminum panels andair-dried for 48 hours, after which the films retained their tackyadhesive characteristics. A

The films were then cured at 350F. for minutes to obtain anon-tacky'coating having a pencil hardness of 7 Clcar film propertiesPaint properties Thick- Swatd Pencil 1mm] nuss lmrdhard- Thlckhard-Formnlatlon number (mils) ncss ncss Flex ncss ncss Flux 1.0 28 2B 2T 1.2F 5T 1. 2 42 HB 2T 1. 0 F 7T 1. 0 20 213 IT 1. 1 F 4T 1.0 10 2B GT 1.1 F3'1 1.0 22 23 IT 1.3 B 4T 1.0 18 2B 1T 1.2 B 4'1 EXAMPLE 5 6 shows thesuperiority of the ketoxime functionality in 7 with the warp threadsrotated 90 in alternate plies to form a l4-ply laminate. Thelaminateshad an average resin content of 29.3 weight percent. Laminates werecured for 24 and 72 hours at 160C. The laminate cured for .2 4 hours hada room temperature flex strength of 16,650 psi, and the 72 hour curegave a laminate having a flex strength of 23,000 psi.

providing hard coatings.

Reasonable modification and variation are within the scope of theinvention which is directed to novel siloxyterminated polybutadiene andcurable. compositions produced by their incorporation ,into; hydroxyl-'functional organosilicon resins.

That which. is'claimed is:'

l. A siloxy-terminated butadiene polymer of the for mula 113-. I RH inwhich R is a monovalent hydrocarbon radical of from 1 to 18 inclusivecarbon atoms, X is a hydrolyzable radical selected from the groupconsisting of the chlorine atom, alkoxy radicals of from 1 to 6inclusive carbon atoms, acyloxy radicals of no more than 8 carbon atomsand ketoxime radicals; a is an integer having a value of 1 or 2; and nis an integer having a sufficiently high value to provide a polydieneaverage molecular weight in the rangeof about 500 to 3,000.

2. The polymer of claim 1 wherein X is an acetoxy radical.

3. The polymer of claim 1 wherein R is selected from the groupconsisting of methyl, phenyl and vinyl radicals.

4. The polymer of claim 1 wherein R is a vinyl radical, Xis an acetoxyradical and a has a value of 2.

5. The polymer of claim 1 wherein R is a methyl radical, X is amethylethylketoxime radical and a has a value of 2.

6. The polymer of claim 1 wherein Ris a methyl radical, X is a chlorineatom and a has a value of 2.

7. Acurable composition comprising the polymer of claim 1 and from 0.5to 5 weight percent, based on the weight of polymer, of an organicperoxide free-radical generating catalyst.

2. The polymer of claim 1 wherein X is an acetoxy radical.
 3. Thepolymer of claim 1 wherein R is selected from the group consisting ofmethyl, phenyl and vinyl radicals.
 4. The polymer of claim 1 wherein Ris a vinyl radical, X is an acetoxy radical and a has a value of
 2. 5.The polymer of claim 1 wherein R is a methyl radical, X is amethylethylketoxime radical and a has a value of
 2. 6. The polymer ofclaim 1 wherein R is a methyl radical, X is a chlorine atom and a has avalue of
 2. 7. A curable composition comprising the polymer of claim 1and from 0.5 to 5 weight percent, based on the weight of polymer, of anorganic peroxide free-radical generating catalyst.